In recent years, touch sensor panels, touch screens, and the like have become available as input devices. Touch screens, in particular, are becoming increasingly popular because of their ease and versatility of operation as well as their declining price. Touch screens can include a touch sensor panel, which can be a clear panel with a touch-sensitive surface, and a display device, such as an LCD panel, that can be positioned partially or fully behind the touch sensor panel so that the touch-sensitive surface can cover at least a portion of the viewable area of the display device. In some devices, the touch screen is protected by a cover glass. Touch screens can allow a user to perform various functions by touching the touch sensor panel using a finger, stylus or other object at a location often dictated by a user interface (UI) being displayed by the display device. In general, touch screens can recognize a touch event and the position of the touch event on the touch sensor panel, and a computing system can then interpret the touch event in accordance with the display appearing at the time of the touch event, and thereafter can perform one or more actions based on the touch event.
Like LCD panels, touch sensor panels in touch screens may be made of glass or other suitable transparent substrate. In some configurations, touch sensor panels can be implemented as an array of pixels formed by multiple drive lines (e.g. rows) crossing over multiple sense lines (e.g. columns), where the drive and sense lines are separated by a dielectric material. In some touch sensor panels, the drive and sense lines can be formed on the top and bottom sides of the same transparent substrate. In other touch sensor panels, the drive and sense lines may be formed on one side of the transparent substrate. The sense lines and drive lines can be formed from a substantially transparent material such as Indium Tin Oxide (ITO), although other materials can also be used. The ITO layer(s) can be deposited on one or both sides of the transparent substrate. Touch sensor panels with double or single sided ITO layers are referred to as double-sided ITO (DITO) touch sensor panels and single-sided ITO (SITO) touch sensor panels, respectively, in this document. DITO and SITO touch sensor panels are widely used in a wide-range of electronic devices, such as tablet PCs, digital music players, cellular telephones, and other wireless handheld devices.
The existing methods of fabricating touch sensor panels require multiple printing steps during the litho/etch patterning process and the subsequent passivation process. The traditional litho/etch process can be expensive because of high equipment and material cost. Thus, it is desirable to reduce the number of printing steps in the fabrication process to reduce the overall manufacturing cost of a touch sensor panel.